JPS60103546A - Variable speed reproduction tracking device of magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To attain stable noise elimination with fast response by providing a pre-tracking monostable multivibrator to attain automatic adjustment at variable speed reprodcution. CONSTITUTION:A noise position is detected from an output signal of a signal processing circuit 17 by a noise detector 18 and the detected noise signal is applied to a noise position automatic control means 19 of the post stage together with an HS signal. The means 19 measures a phase difference or a time difference from the noise signal to the HS signal, allowing to control the pre- tracking MM9 of the next stage so as to be matched with the measured time difference by using the dely amount of the pre-tracking MM9. Then the time difference at both ends of the HS signal and the noise position are measured and the measued time differences are integrated to control the delay amount of the pre-tracking MM9. When the noise position reaches the state that it is coincident to the both ends of the HS signal, the means 19 stops the function. Since a prescribed amount of delay is kept afterward, a phase control circuit 6 of the capstan system is not malfunctioned at all and the noise is kept driven away stably out of the reproduced pattern.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to variable speed playback in a magnetic recording and reproducing device, and particularly to a variable speed playback control circuit suitable for automatically controlling noise.

[Background of the invention]

The applicant is a magnetic recording/reproducing device (hereinafter abbreviated as VTR)
We have previously proposed the following tracking control circuit during variable speed playback (2x/3x quick, reverse playback, etc.).

That is, the noise signal that detects the noise position during variable speed reproduction is compared in phase with the cylinder rotation signal to control and drive the capstan motor responsible for driving the tape. When a normally recorded tape is played back at variable speed, the above method provides sufficient performance.

However, when playing back a tape with severe dropouts due to tape scratches, or when dropouts that tend to occur during transient periods occur, the noise detection means malfunctions, and the phase comparison means is severely disturbed, causing the capstan motor to There was a lot of shaking. For this reason, even after the dropout has disappeared, the capstan motor continues to be out of phase synchronization, resulting in noise appearing on the playback screen.

[Purpose of the invention]

In view of the above points, an object of the present invention is to provide an automatic tracking device that is not affected by mud, dropouts, etc. that occur during variable speed playback.

[Summary of the invention]

The key point of the present invention is to detect the positional deviation between the noise position and the target position in order to automatically drive the noise position to the target position outside the screen at the start of variable speed playback, and to delay the tracking and king by an amount commensurate with this. The above-mentioned automatic noise tracking is interrupted when the amount is changed and the positional deviation is resolved.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings. 6 FIG. 1 is a block diagram of a variable speed playback tracking device showing an embodiment of the present invention. In the figure, 1 is a magnetic tape, 2 is a magnetic tape, and 2 is a magnetic tape.
is a capstan motor, 3 is a summing amplifier, 4 is a speed control circuit, 5 is a frequency generator, 6 is a phase control circuit, 7 is a control head, 8 is a tracking monomulti, 9 is a tracking monomulti, 10 is a reference signal generator, 1
1 is a cylinder motor, 12 is a drive amplifier, 16 is a phase control circuit, 14 is a cylinder rotation phase detector, 15 is a spatula 1. - switch signal generation circuit, 16 is a video head,
17 is a signal processing circuit, 18 is a noise detection circuit, 19 is noise position automatic control means, and 20 is a switch.

Next, the operation will be explained. First, to explain the operation during normal playback, the capstan motor 2 that drives the tape 1 is subjected to speed-phase control by a speed control circuit 4 and a phase control circuit 6, and is controlled at a constant speed and at a predetermined phase. being driven. Further, the cylinder motor 11 is similarly subjected to speed control (not shown) and phase control, and is controlled and driven at a constant speed and a predetermined phase. Here, the phase control circuit 6.degree. 15 controls each of the motors 2 and 11 so that there is no phase difference between the two input signals. Further, the switch 20 is connected to the fixed terminal a side, and the tracking monomulti 8 (hereinafter monomultiple is abbreviated as MM) has a reference signal generator 1o.
However, as shown in FIG. 2(c), a reference signal REF-B is input. Therefore, as shown in FIG. 2(d), the output signal of the tracking MM 8 and a control signal (hereinafter abbreviated as CTL signal) from the control head as shown in FIG. 2(e) are input to the phase control circuit 6. ing. At the same time, the cylinder system phase control circuit 13 receives the above RE from the reference signal generator 1° as shown in FIG. 2(b).
A reference signal REF-A whose phase is opposite to that of F-B is input, and the cylinder motor 11 is input as another input as shown in FIG. 2(a).
A head switch signal (hereinafter abbreviated as H8 signal) obtained by waveform-shaping the rotation detection signal is applied as shown in FIG.

The relationship between the above signals will be explained with reference to FIG. In general, a state in which the tracing relationship of the video head 16 on the tape 1 during recording and playback matches is called just tracking. ) must match the phases of the CTL signals.

Since this phase relationship varies somewhat depending on the VTR set, a tracking MMB is generally provided to enable adjustment.

Next, consider a 5x speed tie as an example of automatic tracking during variable speed playback. At this time, the moving speed of the tape 1, that is, the rotational speed of the capstan motor 2, is set by the speed control circuit 4 to six times the normal speed. In this state, the video head 16 is in a resting state as shown in FIG. 6, as is well known. This figure shows a recording tape pattern and a reproduction trace state, where 21 is a recording track 22 and a reproduction heged trace locus, and 23 is a CTL signal. State A in the figure shows a case where the tracking MM8 is not changed at all, and state B shows a case where the tracking MM8 is set to the optimal tracking state.

At this time, the reproduced envelope waveform from the signal processing circuit 17 is shown correspondingly in FIG.

In FIG. 6, the recording track 21 is for the video,
Therefore, during reproduction, the positive azimuth recording track must be reproduced with the positive azimuth head, and the negative azimuth recording track must be reproduced with the negative azimuth head. When quick playback is performed without changing the tracking as shown in state A in Fig. 6, the parts that trace the same asymmetry track are only the beginning and end of the trace, and the envelope in state A in Fig. 4 is traced. It becomes a waveform. Here, the small portion of the envelope waveform corresponds to the noise portion on the playback screen, and therefore, in this state, more than half is in the noise state.

Furthermore, since both ends of the H8 signal coincide with the vertical retrace period of the reproduced screen, the noise portion becomes extremely unsightly, such as in the center of the screen.

Therefore, in order to achieve optimal tracking state B from state A, it is necessary to move the tracking phase forward or backward by at least 60 degrees. In this state B, the minimum value of the envelope and the noise portion in the reproduced screen coincide with both ends of the H8 signal, that is, the vertical blanking period, and no noise appears on the reproduced screen. Conversely, it is understood that in order to drive the noise in the reproduced screen to the outside of the screen, the tracking should be changed so that the noise position coincides with both ends of the H8 signal.

Therefore, it is understood that during variable speed playback, the switch 20 should be connected to the fixed terminal side, and a pre-tracking MM9 should be provided at the front stage of the tracking MM8 to control the amount of delay, as shown in the actual example in Fig. 1. Ru. In other words, the noise position is detected by the noise detector 18 from the output signal of the signal processing circuit 17, and this detected noise signal is applied together with the H8 signal to the noise position automatic control means 19 in the subsequent stage. , the phase difference b from the noise signal to the H8 signal measures the time difference, and the next stage pre-tracking 1. Control King MM9. After that, the difference of 1 between the noise position and f (both ends of the S signal) is measured again, and the measured time difference is accumulated, and the measurement of the noise position and the control of the delay amount are repeatedly executed as in the Pre-Trazukig MM. , eventually the noise position coincides with both ends of the I (S signal). When this state is reached, the noise position automatic control means 19 stops its function, and the information controlling the pre-tracking MM9 is retained in the me% IJ. Therefore,
After that, the pre-tracking MM 9 does not change due to the occurrence of mud or drop-out, and maintains a constant amount of delay, so the capstan-based phase control circuit 6 never malfunctions and stably removes noise from the playback screen. You can keep pushing.

Next, an embodiment of the automatic noise position control means 19 and the pre-tracking MM 9 is shown in FIG. In the figure, the automatic noise position control means 19 includes a differentiating circuit 24, a pulse generating circuit 25, a counter 26, a gate signal generating circuit 27, 28, 29, an up/down counter 60, and an AND gate S1.32.53.゜It is composed of an inverter 34. On the other hand, the pre-dragging MM9 is a digital delay circuit, and the delay J, ^%/J xc M IJ
-, Bok 6-. It is composed of a count value detector 37 (abbreviated as WWfi under bJ) and a count value detector 37.

Next, the operation will be explained. First, the pre-tracking MM9 has a generally known digital configuration, which will be explained using FIG. 6. First, the reference signal REF-B is the FF56
It is connected to the trigger input terminal T of , and operates at its rising edge. Also, the data input end of FF36 is grounded (logical ant Ll
level), and the detection output of the count value detector 67 is connected to the set input terminal S. The positive phase output of the FF 56 is connected to the preset input terminal PS of the delay counter 35 at the next stage, and a clock signal is applied to its trigger input terminal T. Each bit output of the delay counter 55 is input to a count value detector 57, and when all bits reach 1H', the count value detector 37 inverts the output to %HI. FF36 now
Assume that the output of the delay counter 65 is set to -7'' because the output is at the HE level. In this state, no clock signal is accepted.

Now, the reference signal REF-B is %L# as shown in Fig. 6(a).
When reversed from to H#, the output of Fl16 ((a) in the same figure)
) is inverted to %L#, and the delay counter 35 starts counting clock signals. Let the count value at this time be N and the same figure (C
), the count progresses and the total number of beats on the counter is %H#
Then, the count value detector 57 outputs its output value F) FF5
6's S input (same figure @)) is inverted to %H'. As a result, the FF 56 is set and instantly inverts its output to %HI, the delay counter 55 is preset again, and at the same time, the output of the count value detector 57 also returns to %L#.

At this time, the output of the pre-tracking MM9 is J”
,,l" Considering the output of 36, the delay time TF from when REF-B rises to when FF56 output rises is:
When the black and red cycles are TC and the preset value is the number of bits of the NO delay counter 55 as n, the following equation is given.

TP = (2n-1-No) TO Therefore, when NO in the above equation is changed, the delay time TP also changes, and the width of the change is given by the following equation.

TP = 'l'c ~ (2n-1)'l'c For example, if TO = 0.5ms # n :6, TPO
The maximum value is 5t5ms, which is approximately one cycle of REF-B (55me).

Next, the operation of the noise position self-excitation control means 19 will be explained with reference to FIG. The basic operation is to operate the up/down counter 30 until one end of the noise signal and the H8 signal match, and then use the output information of the next stage pre-tracking MM9.
This is used to set a preset value for the delay counter 35 within.

First, the gate signal generating circuit 27 generates the gate signal G as shown in FIG. 7(b) from both ends of the H8 signal. The gate signal G and H8 signal are inputted to the next stage latches 28 and 29, and then taken from the pulse generating circuit 25 to the pulse generator.

On the other hand, the noise signal is applied to the pulse generation circuit 25 via the AND gate 51. This nokurusu generation circuit 2
5, the above-mentioned lubricious pulse L is first output together with the input of the noise signal, and immediately after that, the trigger pulse P is output.

This trigger pulse P is applied to the trigger input terminal T of the counter 26 and up/down counter 30 via an AND gate 5.2.5S. When the quick command signal is input, the counter 26 is instantaneously reset by the output of the differentiating circuit 24, and its negative phase output page is at the %H' level. Therefore, in the initial state, AND gate 31 passes the noise signal.

Suppose now that the noise signal arrives in the state of A in FIG.
The retained information of 9 is 1H'.

At this time, AND gate S6 is in an open state, and
The gate 62 is closed by the inverter 34.

Therefore, the trigger pulse P subsequently output from the pulse generating circuit 25 is applied only to the up/down counter 30. Here, the mode of the up/down counter 30 is such that it counts up when the input to its V/D terminal is %Hz. The up/down counter 50 is initialized when the power is turned on, and the initial state Mo of i-1 is MO=2. Here, n is the number of bits of the counter 30, which is the same number of bits as the delay counter 35. Therefore, depending on the trigger pulse P in state A, the count value M of the up/down counter 60 becomes Mo+1=2-)-1.

As a result, the preset value of the delay counter 35 is also 2.
+1, the delay amount of the pre-tracking MM9 becomes shorter. Therefore, in Figure 1, the phase of the reference signal input to phase control circuit B is slightly advanced, so tape 1
will also follow this and become a little more advanced. At this time, the third
As can be seen from the figure, as the tape 1 advances, the position of the minimum value of the reproduced envelope waveform approaches the upper end of the tape 1. In other words, the noise level β'- on the reproduced screen approaches the lower side of the screen, and the noise signal in FIG. 7(c) moves backward.

As a result, the noise position becomes close to the falling edge of the H8 signal. Furthermore, in this state B, the up/down counter 30 repeats counting in the upward direction in the same manner as described above, and the noise position finally reaches the falling edge of the H8 signal and the 'tb gate signal G'.
The state becomes C, which matches the L' portion.

In the above explanation, we have explained the case where the noise signal arrives at the *Hl level position of the FiH8 signal, but if the noise signal arrives at the 'L# level position of the H8 signal, the up mode is changed to the down mode in the above explanation. It is only necessary to consider the moving direction of the noise position in the forward direction.

When this state C is reached, the latch 28 in FIG. 5 receives 1L# of the gate signal G and inverts its output to 1Ll. As a result, the AND gate 33 is closed, and the AND gate 33 is closed.
The D gate 32 is in an open state. In other words, the up/down counter 3o holds the information, and the counter 26 counts the trigger pulses P from the pulse generating circuit 25.

The function of this counter 26 is to stop the operation of the automatic noise position control means 19 when state C continues for a predetermined number of times. Therefore, when the state C is cycled X times, the counter 26 counts the trigger pulse P X times and inverts the negative phase output to Ll. AND gate 6 by kneading
Since the value 1 is silent, subsequent noise signals are not accepted, so the information held in the up/down counter 30 and the counted value of the delay counter 35 never change.

It will be understood that when quick playback is executed again without turning off the power to the VTR, the information in the up/down counter 30 is retained, so that the noise position immediately reaches state C in FIG. 7.

Also, when changing the tape and performing quick playback, the tracking MM8 had to be re-adjusted to W4 to track down the noise position. However, in the embodiment of the present invention, the differentiating circuit 24 shown in FIG. If it appears, you can automatically remove it from the screen by performing the operation described above.

In the above embodiment, as shown in FIG. 7, even if the noise position is close to the rising edge of the H8 signal, the system drives the noise to the falling edge of the H8 signal. FIG. 8 shows an embodiment of a method for moving this noise position to the near end of the H8 signal. This figure shows only the noise position automatic control means 19 of FIG. 5, but a waveform shaping circuit 38 is added to the structure of FIG.

The operation will be explained with reference to FIG. The H8 signal is input to the waveform shaping circuit 38, and the H82 signal shown in FIG. 9(b) is generated by doubling the H8 signal using a delay means or the like. This signal H82 is applied to the next stage latch 29, and the fifth
It is captured by the latch pulse L in the same way as shown in the figure. The output of latch 29 similarly determines the up/down mode of up/down counter 50. When the noise signal is close to the falling edge of the H8 signal, as in state A in FIG. Drive it to the falling edge. Conversely, when the noise position is close to the rising edge of the H8 signal, as in state B, the output of the latch 29 is
Then, the up/down counter 5o counts in the down mode. As a result, the delay time of the pre-tracking MM 9 in FIG. 1 is large and the phase of the shift tape 1 is slow 9, so that the noise position eventually moves forward.

In the embodiment shown in FIG. 8, as shown in FIG. 9, it is sufficient that the movement range of the noise position is half that of the H8 signal. This means that the configurations of the up/down counter 3o and the delay counter 35 can be reduced by one bit.In the explanation of the noise position automatic control means 19 in the embodiment of 0 or more, the up/down counter 5° is used. Similar automatic control can be achieved by using a noise position measuring means, an adder, and a memory means. Next, one embodiment of this method will be described.

FIG. 10 shows another embodiment of the present invention. This figure shows only the noise position automatic control means 19 in FIGS. 1 and 5, the controller 39, and the time difference measuring means 4.
0, latches 41, 42, adder 43, memory means 44
Consists of. The controller 39 receives a still command signal,
The H8 signal and the noise position signal are input, and the latches 41 and 42 of the time difference measuring means 4°27 are controlled by the α output.

Next, the operation will be explained. First, when a still command signal is input, the controller 39 operates the time difference measuring means 40. This time difference measuring means 4o calculates H8 from the noise position signal.
Measure 1iJl when reaching the signal end. This measurement can be easily realized using a general counter means and a clock signal. When the measurement is completed, measurement information is input to the latch 41 in response to a latch command from the controller 39. At the same time, the contents of the memory means 44 are also taken into the latch 42.

Each latch information is applied to an adder 45, and the added output is recorded in the memory means 44 again.

The output of the memory means 44 is the up/down counter 3 in FIG.
Similarly to the output of 0, the preset value of the delay counter 65 of the next-stage Brittler King MM9 is determined.

Here, the contents of the memory means 44 are reset every time the power is turned on. Furthermore, with the method of this embodiment, it is possible to drive most of the noise position out of the playback screen with the first operation, and the response is fast. Although not shown in FIG. 10, a means for stopping this function at the time when the automatic noise position control is completed can be easily realized in the same manner as in FIG. 5.

According to the embodiments described above, pre-tracking M M
9 to automatically perform the adjustment during variable speed playback, it is not only possible to eliminate the conventional adjustment, but also to stop this function once the automatic adjustment is completed after a predetermined period of time. It is possible to create a system that does not malfunction at all even when there is noise at the output or recording joints.

By retaining automatically adjusted information, the response is extremely fast and noise can be pushed out of the playback screen when writing and playing at variable speeds.

〔Effect of the invention〕

According to the present invention, the automatic adjustment function can be stopped once the automatic adjustment is completed, instead of being able to eliminate the conventional adjustment by automatically performing the PJ adjustment during variable speed playback. Good, it is possible to stably suppress noise such as subsequent dropouts and noise at recording seams.

Furthermore, when the automatically adjusted information is retained and variable speed playback is performed again, the automatic adjustment is started from this retained information, making it possible to instantly eliminate noise, which has the effect of achieving stable and fast-response noise elimination. .

[Brief explanation of drawings]

Fig. 1 is a block diagram showing an embodiment of the present invention, Fig. 2 is a waveform diagram of main parts for explaining the operation of Fig. 1, Fig. 3 is a tape pattern diagram, and Fig. 4 is the operation of Fig. 1. Figure 5 is a block diagram showing an example of the constituent factors in Figure 1, Figures 6 and 7 are waveform diagrams of the main parts of Figure 5,
FIG. 8 is a block diagram showing another embodiment of FIG. 5;
This figure is a waveform diagram of the main part of FIG. 8, and FIG. 10 is a block diagram showing another embodiment of FIG. 5. 2...Capstan motor, 6...Phase control circuit, 8...Toronokink mono multi, 9...Bri tracking mono multi, 19...Noise position automatic control means, 30...Up Down counter, 35...Delay counter. Agent square filler Nao T#i Akira Daidai / Zuzo 2 Hidai 3 Figure 4 Z (1) H3 B Figure δ Figure q Figure A D Figure 10

Claims (1)

[Claims] 1. In a variable speed reproducing device of a magnetic recording and reproducing device, there is provided a tracking adjustment means, a delay adjustment means for assisting the tracking adjustment means, and a delay amount setting of the adjustment means. A variable speed playback truck for a magnetic recording and playback device, characterized in that it has a means for detecting a noise position on a playback screen, and a means for automatically controlling the delay amount setting means according to the output of the noise position detection means. King device. 2. The magnetic recording and reproducing apparatus according to claim 1, wherein when the automatic control means completes the setting of the delay amount setting means, the automatic control means stops functioning. Variable speed playback tracking device. 6. The magnetic recording and reproducing device according to claim 1, wherein when the automatic control means completes the setting of the delay setting means, setting information for determining the amount of delay is retained. Device variable speed playback tracking device. 4. The variable speed reproduction tracker and king device of the magnetic recording and reproduction apparatus according to any one of claims 1 to 6, wherein the delay amount setting means has an up/down counter or a memory circuit. . 5. The noise position detecting means receives a head switching signal as an input, and detects the noise position using a signal of twice the frequency synchronized with this signal. Variable speed playback truck 91'j of any magnetic recording/playback device? equipment.